This invention is concerned with agents for the treatment of primary, metastatic and residual cancer in mammals (including humans) by inducing the immune system of the mammal or human afflicted with cancer to mount an attack against the tumour lesion. In particular, the invention pertains to the use of whole-cells, derivatives and portions thereof with or without vaccine adjuvants and/or other accessory factors. More particularly, this disclosure describes the use of particular combinations of whole-cells and derivatives and portions thereof that form the basis of treatment strategy.
It is known in the field that cancerous cells contain numerous mutations, qualitative and quantitative, spatial and temporal, relative to their normal, non-cancerous counterparts and that at certain periods during tumour cells"" growth and spread a proportion of these are capable of being recognised by the hosts"" immune system as abnormal. This has led to numerous research efforts world-wide to develop immunotherapies that harness the power of the hosts"" immune system and direct it to attack the cancerous cells, thereby eliminating such aberrant cells at least to a level that is not life-threatening (reviewed in Maraveyas, A. and Dalgleish, A. G. 1977 Active immunotherapy for solid tumours in vaccine design in The Role of Cytokine Networks, Ed. Gregoriadis et al., Plenum Press, New York, pages 129-145; Morton, D. L. and Ravindranath, M. H. 1996 Current concepts concerning melanoma vaccines in Tumor Immunologyxe2x80x94Immunotherapy and Cancer Vaccines, ed. Dalgleish, A. G. and Browning, M., Cambridge University Press, pages 241-268. See also other papers in these publications for further detail).
Numerous approaches have been taken in the quest for cancer immunotherapies, and these can be classified under five categories:
Efforts to stimulate the immune system non-specifically date back over a century to the pioneering work of William Coley (Coley, W. B., 1894 Treatment of inoperable malignant tumours with toxins of erisipelas and the Bacillus prodigosus. Trans. Am. Surg. Assoc. 12: 183). Although successful in a limited number of cases (e g. BCG for the treatment of urinary bladder cancer, IL-2 for the treatment of melanoma and renal cancer) it is widely acknowledged that non-specific immunomodulation is unlikely to prove sufficient to treat the majority of cancers. Whilst non-specific immune-stimulants may lead to a general enhanced state of immune responsiveness, they lack the targeting capability and also subtlety to deal with tumour lesions which have many mechanisms and plasticity to evade, resist and subvert immune-surveillance.
Passive immunotherapy in the form of antibodies, and particularly monoclonal antibodies, has been the subject of considerable research and development as anti-cancer agents. Originally hailed as the magic bullet because of their exquisite specificity, monoclonal antibodies have failed to live up to their expectation in the field of cancer immunotherapy for a number of reasons including immune responses to the antibodies themselves (thereby abrogating their activity) and inability of the antibody to access the lesion through the blood vessels. To date, three products have been registered as pharmaceuticals for human use, namely Panorex (Glaxo-Welicome), Rituxan (IDEC/Genentech/Hoffman la Roche) and Herceptin (Genentech/Hoffman la Roche) with over 50 other projects in the research and development pipeline. Antibodies may also be employed in active immunotherapy utilising anti-idiotype antibodies which appear to mimic (in an immunological sense) cancer antigens. Although elegant in concept, the utility of antibody-based approaches may ultimately prove limited by the phenomenon of xe2x80x98immunological escapexe2x80x99 where a subset of cancer cells in a mammalian or human subject mutates and loses the antigen recognised by the particular antibody and thereby can lead to the outgrowth of a population of cancer cells that are no longer treatable with that antibody.
Drawing on the experience in vaccines for infectious diseases and other fields, many researchers have sought to identify antigens that are exclusively or preferentially associated with cancer cells, namely tumour specific antigens (TSA) or tumour associated antigens (TAA), and to use such antigens or fractions thereof as the basis for specific active immunotherapy.
There are numerous ways to identify proteins or peptides derived therefrom which fall into the category of TAA or TSA. For example, it is possible to utilise differential display techniques whereby RNA expression is compared between tumour tissue and adjacent normal tissue to identify RNAs which are exclusively or preferentially expressed in the lesion. Sequencing of the RNA has identified several TAA and TSA which are expressed in that specific tissue at that specific time, but therein lies the potential deficiency of the approach in that identification of the TAA or TSA represents only a xe2x80x9csnapshotxe2x80x9d of the lesion at any given time which may not provide an adequate reflection of the antigenic profile in the lesion over time. Similarly a combination of cytotoxic T lymphocyte (CTL) cloning and expression-cloning of cDNA from tumour tissue has lead to identification of many TAA and TSA, particularly in melanoma. The approach suffers from the same inherent weakness as differential display techniques in that identification of only one TAA or TSA may not provide an appropriate representation of a clinically relevant antigenic profile.
Over fifty such subunit vaccine approaches are in development for the treatment of a wide range of cancers, although none has yet received marketing authorisation for use as a human pharmaceutical product. In a similar manner to that described for antibody-based approaches above, subunit vaccines may also be limited by the phenomenon of immunological escape.
The majority of gene therapy trials in human subjects have been in the area of cancer treatment, and of these a substantial proportion have been designed to trigger and/or amplify patients"" immune responses. Of particular note in commercial development are Allovectin-7 and Leuvectin, being developed by Vical Inc for a range of human tumours, CN706 being developed by Calydon Inc for the treatment of prostate cancer, and StressGen Inc.""s stress protein gene therapy for melanoma and lung cancer. At the present time, it is too early to judge whether these and the many other xe2x80x98immuno-gene therapiesxe2x80x99 in development by commercial and academic bodies will ultimately prove successful, but it is widely accepted that commercial utility of these approaches are likely to be more than a decade away.
Tumours have the remarkable ability to counteract the immune system in a variety of ways including: downregulation of the expression of potential target proteins; mutation of potential target proteins; downregulation of surface expression of receptors and other proteins; downregulation of MHC class I and II expression thereby disallowing direct presentation of TAA or TSA peptides; downregulation of co-stimulatory molecules leading to incomplete stimulation of T-cells leading to anergy; shedding of selective, non representative membrane portions to act as decoy to the immune system; shedding of selective membrane portions to anergise the immune system; secretion of inhibitory molecules; induction of T-cell death; and many other ways. What is clear is that the immunological heterogeneity and plasticity of tumours in the body will have to be matched to a degree by immunotherapeutic strategies which similarly embody heterogeneity. The use of whole cancer cells, or crude derivatives thereof, as cancer immunotherapies can be viewed as analogous to the use of whole inactivated or attenuated viruses as vaccines against viral disease. The potential advantages are:
(a) whole cells contain a broad range of antigens, providing an antigenic profile of sufficient heterogeneity to match that of the lesions as described above;
(b) being multivalent (i.e. containing multiple antigens), the risk of immunological escape is reduced (the probability of cancer cells xe2x80x98losingxe2x80x99 all of these antigens is remote); and
(c) cell-based vaccines include TSAs and TAAs that have yet to be identified as such; it is possible if not likely that currently unidentified antigens may be clinically more relevant than the relatively small number of TSAs/TAAs that are known.
Cell-based vaccines fall into two categories. The first, based on autologous cells, involves the removal of a biopsy from a patient, cultivating tumour cells in vitro, modifying the cells through transfection and/or other means, irradiating the cells to render them replication-incompetent and then injecting the cells back into the same patient as a vaccine. Although this approach enjoyed considerable attention over the past decade, it has been increasingly apparent that this individually-tailored therapy is inherently impractical for several reasons. The approach is time consuming (often the lead time for producing clinical doses of vaccine exceeds the patients"" life expectancy), expensive and, as a xe2x80x98bespokexe2x80x99 product, it is not possible to specify a standardised product (only the procedure, not the product, can be standardised and hence optimised and quality controlled). Furthermore, the tumour biopsy used to prepare the autologous vaccine will have certain growth characteristics, interactions and communication with surrounding tissue that makes it somewhat unique. This alludes to a potentially significant disadvantage to the use of autologous cells for immunotherapy: a biopsy which provides the initial cells represents an immunological snapshot of the tumour, in that environment, at that point in time, and this may be inadequate as an immunological representation over time for the purpose of a vaccine with sustained activity that can be given over the entire course of the disease.
The second type of cell-based vaccine and the subject of the current invention describes the use of allogeneic cells which are be genetically (and hence immunologically) mismatched to the patients. Allogeneic cells benefit from the same advantages of multivalency as autologous cells. In addition, as allogeneic cell vaccines can be based on immortalised cell lines which can be cultivated indefinitely in vitro, thus this approach does not suffer the lead-time and cost disadvantages of autologous approaches. Similarly the allogeneic approach offers the opportunity to use combinations of cells types which may match the disease profile of an individual in terms of stage of the disease, the location of the lesion and potential resistance to other therapies.
There are numerous published reports of the utility of cell-based cancer vaccines (see, for example, Dranoff, G. et al. WO 93/06867; Gansbacher, P. WO 94/18995; Jaffee, E. M. et al. WO 97/24132; Mitchell, M. S. WO 90/03183; Morton, D. M. et al. WO 91/06866). These studies encompass a range of variations from the base procedure of using cancer cells as an immunotherapy antigen, to transfecting the cells to produce GM-CSF, IL-2, interferons or other immunologically-active molecules and the use of xe2x80x98suicidexe2x80x99 genes. Groups have used allogeneic cell lines that are HLA-matched or partially-matched to the patients"" haplotype and also allogeneic cell lines that are mismatched to the patients"" haplotype in the field of melanoma and also mismatched allogeneic prostate cell lines transfected with GM-CSF.
The invention disclosed here relates to a product comprised of specific combinations of cell lines intended for use as an allogeneic immunotherapy agent for the treatment of prostate cancer in humans. The heterogeneity of the immunotherapeutic described herein matches the heterogeneity of the antigenic profile in the target prostate cancer and immunises the recipients with many of the potential TAA and TSA which are expressed at various stages of the disease. The cell lines are chosen from appropriate cell lines which possess the following characteristics: the cells are immortalised, prostate or metastatic prostate in origin, show good growth in large scale cell culture, and are well characterised allowing for quality control and reproducible production of the component cell lines.
The invention disclosed herein also relates to a product comprising of a combination of cells lines described above whereby the cell lines are chosen to allow for the maximum mismatch of haplotype with the intended patient population, thereby ensuring the maximum allogeneic potential and subsequent immune response to the product.
The invention described discloses a vaccine comprising a combination of three different cell lines prepared from primary or metastatic prostate cancer biopsy material using methods known in the art (reviewed and cited in Rhim, J. S. and Kung, H-F., 1997 Critical Reviews in Oncogenesis 8(4):305-328) and/or selected from Group A (cell lines derived from primary prostate cancer lesions) and Group B (cell lines derived from metastatic prostate cancer lesions) listed in Table 1.
In one embodiment, the combination of cell lines consists of three different cell lines derived from primary prostate cancer lesions.
In another embodiment, the combination consists of two different cell lines derived from primary prostate cancer lesions and one cell line derived from a metastatic prostate cancer lesion.
In another embodiment, the combination consists of one cell line derived from a primary prostate cancer lesion combined with two different cell lines derived from metastatic prostate cancer lesions.
In a further embodiment, the combination consists of three different cell lines derived from metastatic prostate cancer lesions.
The cell lines are lethally irradiated utilising gamma irradiation at 50-300 Gy to ensure that they are replication incompetent.
The cell lines and combinations referenced above, to be useful as immunotherapy agents must be frozen to allow transportation and storage, therefore a further aspect of the invention is any combination of cells referenced above formulated with a cryoprotectant solution. Suitable cryoprotectant solutions may include but are not limited to, 10-30% v/v aqueous glycerol solution, 5-20% v/v dimethyl sulphoxide or 5-20% w/v human serum albumin may be used either as single cryoprotectants or in combination.
A further embodiment of the invention is the use of the cell line combinations with non-specific immune stimulants such as BCG or M. Vaccae, Tetanus toxoid, Diphtheria toxoid, Bordetella Pertussis, interleukin 2, intedeukin 12, interleukin 4, interleukin 7, Complete Freund""s Adjuvant, Incomplete Freund""s Adjuvant or other non-specific agents known in the art. The advantage is that the general immune stimulants create a generally enhanced immune status whilst the combinations of cell lines, both add to the immune enhancement through their haplotype mismatch and target the immune response to a plethora of TAA and TSA as a result of the heterogeneity of their specific origins.